Further Investigations into the Synthesis and Characterization of Halo-Boron-Arsenic Compounds: X-Ray Crystal Structures of X 3 ·As(SiMe 3 ) 3 (X = Cl,I) and [I 2 BAs(SiMe 3 ) 2 ] 2

Abstract

A low-temperature (−78°C) 1:1 mole ratio reaction of BI₃ with As(SiMe₃)₃, produced the 1:1 Lewis acid-base adduct I₃B·As(SiMe₃)₃ (l), whereas the identical reaction performed at room temperature (previously reported)¹ produced the dimeric compound, [I₂BAs(SiMe₃)₂]₂ (2). Full characterization of compound 1 was conducted, including a single-crystal X-ray structural determination. The previously unreported X-ray crystal structures of 2 and Cl₃ B·As(SiMe₃)₃ (3) have also been elucidated. Crystals of 1 belong to the orthorhombic space group Pbca, with a = 13.8673(13), b = 17.5885(8), c = 22.8784(22) Å, V = 5580.1(8) ų, D_calc = 1.853 g cm⁻³ for Z = 8, and the B-As bond length is 2.104(15)Å. Crystals of 2 belong to the monoclinic space group P2₁/n , with a = 9.836(5), b = 13.682(3), c = 11.701(6) Å, V = 1545.8 (12) ų,D _calc= 2.088 g cm⁻³ for Z = 4, and the average B-As bond length is 2.13 Å. Compound 3 crystallizes in the orthorhombic space group Pbca, with a = 13.4109(2), b = 17.1371(2), c = 21.7996(3) Å, V=5010.07(12) ų, D_calc= 1.336 g cm⁻³ for Z = 8, and the B-As bond length is 2.118(6) Å.